Improve type determination for factory beans during condition evaluation

Previously, BeanTypeRegistry did not correctly determine the type
that would be created by a factory bean if that factory bean was
returned from a bean method with arguments on a configuration class
found via component scanning.

The key difference is that bean definitions for bean methods on
configuration classes found via component scanning use ASM-based
metadata rather than reflection-based metadata. The ASM-based method
data does not provide direct access to the Method that will create the
bean. In this case, BeanTypeRegistry was falling back to looking for
a method with the matching name and no arguments. Therefore, if
the bean method had any arguments it would fail to find the method
and would, therefore, be unable to determine the type of bean
produced by the factory bean.

This commit updates BeanTypeRegistry to use logic that is very similar
to Spring Framework's ConstructorResolver's
resolveFactoryMethodIfPossible method to locate the method that will
produce the factory bean. It looks for a single method with
the required name with any number of arguments. If it finds multiple
methods with the required name and different arguments it returns
null, just as ConstructorResolver does.

Closes gh-6755

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/BeanTypeRegistry.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,6 +37,7 @@ import org.springframework.beans.factory.SmartInitializingSingleton;
 import org.springframework.beans.factory.annotation.AnnotatedBeanDefinition;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.beans.factory.support.AbstractBeanDefinition;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.core.ResolvableType;
@@ -137,8 +138,34 @@ abstract class BeanTypeRegistry {
 				.getBeanDefinition(definition.getFactoryBeanName());
 		Class<?> factoryClass = ClassUtils.forName(factoryDefinition.getBeanClassName(),
 				beanFactory.getBeanClassLoader());
-		return ReflectionUtils.findMethod(factoryClass,
-				definition.getFactoryMethodName());
+		Method uniqueMethod = null;
+		for (Method candidate : getCandidateFactoryMethods(definition, factoryClass)) {
+			if (candidate.getName().equals(definition.getFactoryMethodName())) {
+				if (uniqueMethod == null) {
+					uniqueMethod = candidate;
+				}
+				else if (!matchingArguments(candidate, uniqueMethod)) {
+					return null;
+				}
+			}
+		}
+		return uniqueMethod;
+	}
+
+	private Method[] getCandidateFactoryMethods(BeanDefinition definition,
+			Class<?> factoryClass) {
+		return shouldConsiderNonPublicMethods(definition)
+				? ReflectionUtils.getAllDeclaredMethods(factoryClass)
+				: factoryClass.getMethods();
+	}
+
+	private boolean shouldConsiderNonPublicMethods(BeanDefinition definition) {
+		return (definition instanceof AbstractBeanDefinition)
+				&& ((AbstractBeanDefinition) definition).isNonPublicAccessAllowed();
+	}
+
+	private boolean matchingArguments(Method candidate, Method current) {
+		return Arrays.equals(candidate.getParameterTypes(), current.getParameterTypes());
 	}
 
 	private Class<?> getDirectFactoryBeanGeneric(

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/condition/ConditionalOnMissingBeanTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,10 +23,15 @@ import org.springframework.beans.factory.annotation.Value;
 import org.springframework.beans.factory.support.BeanDefinitionBuilder;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.boot.autoconfigure.PropertyPlaceholderAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.scan.ScannedFactoryBeanConfiguration;
+import org.springframework.boot.autoconfigure.condition.scan.ScannedFactoryBeanWithBeanMethodArgumentsConfiguration;
 import org.springframework.boot.test.EnvironmentTestUtils;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.ComponentScan.Filter;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.FilterType;
 import org.springframework.context.annotation.Import;
 import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
 import org.springframework.context.annotation.ImportResource;
@@ -130,6 +135,27 @@ public class ConditionalOnMissingBeanTests {
 				equalTo("fromFactory"));
 	}
 
+	@Test
+	public void testOnMissingBeanConditionWithComponentScannedFactoryBean() {
+		this.context.register(ComponentScannedFactoryBeanBeanMethodConfiguration.class,
+				ConditionalOnFactoryBean.class,
+				PropertyPlaceholderAutoConfiguration.class);
+		this.context.refresh();
+		assertThat(this.context.getBean(ExampleBean.class).toString(),
+				equalTo("fromFactory"));
+	}
+
+	@Test
+	public void testOnMissingBeanConditionWithComponentScannedFactoryBeanWithBeanMethodArguments() {
+		this.context.register(
+				ComponentScannedFactoryBeanBeanMethodWithArgumentsConfiguration.class,
+				ConditionalOnFactoryBean.class,
+				PropertyPlaceholderAutoConfiguration.class);
+		this.context.refresh();
+		assertThat(this.context.getBean(ExampleBean.class).toString(),
+				equalTo("fromFactory"));
+	}
+
 	@Test
 	public void testOnMissingBeanConditionWithFactoryBeanWithBeanMethodArguments() {
 		this.context.register(FactoryBeanWithBeanMethodArgumentsConfiguration.class,
@@ -241,6 +267,18 @@ public class ConditionalOnMissingBeanTests {
 		}
 	}
 
+	@Configuration
+	@ComponentScan(basePackages = "org.springframework.boot.autoconfigure.condition.scan", includeFilters = @Filter(type = FilterType.ASSIGNABLE_TYPE, classes = ScannedFactoryBeanConfiguration.class))
+	protected static class ComponentScannedFactoryBeanBeanMethodConfiguration {
+
+	}
+
+	@Configuration
+	@ComponentScan(basePackages = "org.springframework.boot.autoconfigure.condition.scan", includeFilters = @Filter(type = FilterType.ASSIGNABLE_TYPE, classes = ScannedFactoryBeanWithBeanMethodArgumentsConfiguration.class))
+	protected static class ComponentScannedFactoryBeanBeanMethodWithArgumentsConfiguration {
+
+	}
+
 	@Configuration
 	protected static class FactoryBeanWithBeanMethodArgumentsConfiguration {
 		@Bean

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/condition/scan/ScannedFactoryBeanConfiguration.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2012-2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.autoconfigure.condition.scan;
+
+import org.springframework.beans.factory.FactoryBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBeanTests.ExampleBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBeanTests.ExampleFactoryBean;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Configuration for a factory bean produced by a bean method on a configuration class
+ * found via component scanning.
+ *
+ * @author Andy Wilkinson
+ */
+@Configuration
+public class ScannedFactoryBeanConfiguration {
+
+	@Bean
+	public FactoryBean<ExampleBean> exampleBeanFactoryBean() {
+		return new ExampleFactoryBean("foo");
+	}
+
+}

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/condition/scan/ScannedFactoryBeanWithBeanMethodArgumentsConfiguration.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2012-2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.autoconfigure.condition.scan;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBeanTests.ExampleFactoryBean;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Configuration for a factory bean produced by a bean method with arguments on a
+ * configuration class found via component scanning.
+ *
+ * @author Andy Wilkinson
+ */
+@Configuration
+public class ScannedFactoryBeanWithBeanMethodArgumentsConfiguration {
+
+	@Bean
+	public Foo foo() {
+		return new Foo();
+	}
+
+	@Bean
+	public ExampleFactoryBean exampleBeanFactoryBean(Foo foo) {
+		return new ExampleFactoryBean("foo");
+	}
+
+	static class Foo {
+
+	}
+
+}